Question: Ben starts counting at 29, and he counts by fours. If 29 is the 1st number that Ben counts. what is the 9th number that he counts?
Solution: What is the first number that he counts? $29$ What is the second number that he counts? $\begin{align*}&29 + 4 \\ &= 33\end{align*}$ What is the third number that he counts? $\begin{align*}&29 + 4 + 4 \\ &= 29 + (2 \times 4) \\ &= 37\end{align*}$ What is the 9th number that he counts? $\begin{align*}&29 + (8\times4) \\ &= 29 + 32 \\ &= 61\end{align*}$